DE 44 36 397 A1 relates to a device for the aftertreatment of exhaust gases. A device for the aftertreatment of exhaust gases of a compression-ignition internal combustion engine is disclosed, in which, in order to improve the operation of a reducing catalytic converter, a reducing agent is input into the exhaust gas which is fed to the catalytic converter. Here, the input of the reducing agent takes place via an electrically controlled metering valve which is combined in a common housing with a control valve. The control valve serves for the controlled introduction of supplied compressed air, in which a quantity of reducing agent which is predefined via the metering valve is prepared and is subsequently input intermittently into the exhaust gas. This serves, in particular, for avoiding urea deposits and adhesions on the metering valve and control valve, in addition to optimum preparation of the reducing agent which is introduced.
DE 198 56 366 C1 relates to an apparatus and a method for the aftertreatment of exhaust gases of an internal combustion engine which operates with excess air. An apparatus for the aftertreatment of exhaust gases is proposed which comprises a reduction catalytic converter which serves for the reduction of NOx constituent parts in the exhaust gas. Furthermore, the apparatus comprises an electrically actuable metering device for the controlled introduction of reducing agent in an exhaust gas line upstream of the reducing agent catalytic converter, and a device for cooling the metering device. The metering device comprises an injection valve which is enclosed by a double-walled valve receiving body which is connected directly to the exhaust gas line. Furthermore, the metering device comprises a compressed air generation device which blows compressed air into an air gap between an outer wall and an inner wall of the valve receiving body in order to cool at least those parts of the injection valve which are close to the exhaust gas.
DE 10 2012 201 203 relates to a water-cooled metering module for metering a reducing agent into an exhaust gas section of an internal combustion engine. The metering module comprises at least one cooling element which is flowed through by a cooling fluid which can serve for cooling the internal combustion engine. An electrical contact is situated in the upper region of the metering module. The metering module is enclosed by a full enclosure. The full enclosure comprises an upper and lower cooling element which are flowed through by a directed cooling fluid flow starting from the valve tip region in the direction of the electrical contact.
In order for the valve tip of the metering module to be as close as possible to the exhaust gas flow, the valve seat is actively cooled in the metering modules. This takes place by way of a connection of the cooling element, for example, to the coolant circuit of the vehicle. This ensures that the temperature of the valve tip does not exceed 120° C. during operation, even if the metering module is positioned close to the exhaust gas. Because of the concept, however, a connection piece of the metering module, via which connection piece the operating medium/additive which is to be metered in, for example urea/water solution or urea or the like, flows into the metering module, is subjected to the surrounding temperature. In critical operating states, for example at high external ambient temperatures during operation or in the case of hot soak operations, the connection piece can be heated in an undesirable manner and can introduce heat into the interior of the metering module as a result. The connection piece region which lies exposed because of the concept is very critical with regard to heating of the metering module.